With the rapid development of mobile communication technology, mobile communication networks are being extensively used and the number of mobile communication users is increasing sharply. MBMS technology is employed by most of the mobile communication networks.
A MBMS service that provides a broadcasting service to a mobile phone in a Third Generation Partnership Project (3GPP) wireless communication system has been standardized in various groups of the 3GPP.
There exist two transmission modes to provide the MBMS service: point-to-point transmission (p-t-p) and point-to-multipoint transmission (p-t-m).
Generally, point-to-point transmission is used to transfer MEMS specific control/user plane information as well as dedicated control/user plane information between one network and one User Equipment (UE) in a Radio Resource Connection (RRC) Connected Mode. It is only used for the multicast mode of MBMS and for services identified in the list of MBMS Selected Services.
Point-to-multipoint transmission is used to transfer MBMS specific control and/or user plane information between the network and several UEs in RRC Connected or Idle Mode. It is used for broadcast or multicast mode of MBMS.
MBMS Counting is used to determine the optimum transmission mechanism for a given service. The need for counting is indicated in the notification, and achieved by requesting UEs, which belong to the same MEMS service group, to respond to counting by sending MBMS COUNTING RESPONSE signaling flow to a Controlling Radio Network Controller (CRNC). To be specific:                in case the UEs are in idle mode, the counting response refers to a RRC connection establishment procedure;        in case the UEs are in URA_PCH or CELL_PCH state, the counting response refers to a cell update procedure;        in case the UEs are in CELL_FACH state, the counting response refers to a signaling on CCCH or DCCH.        
Since it is desirable to avoid bringing a large number of UEs for counting purposes to RRC connection mode in a specific cell at the same time (RACH load, etc), RRM may control the load by setting an access “probability factor”.
Upon receiving the MBMS ACCESS INFORMATION message including MBMS service and probability factor a UE has joined or selected, the UE shall start counting response procedure for each joined or selected service:
If the UE is in idle mode, a random number “rand” will be drawn and uniformly distributed in the range: 0<rand<1; if “rand” is lower than the value indicated by “Access probability factor-Idle” for the concerned service, then UE will indicate upper layers that an RRC connection is required to establish so as to receive the concerned MBMS service, meanwhile the establishment cause is set to “MBMS reception”; if the RRC connection establishment and/or cell update succeeds, the procedure ends.
The main purpose of counting is to choose the best transmission mode: p-t-p or p-t-m. Generally, if the number of UE which responds to the counting exceeds a threshold, p-t-m will be adopted; otherwise p-t-p will be adopted.
Normally, the counting procedure will be tried several times. To be specific, the counting procedure firstly starts with a small PF to avoid access congestion. If the threshold is not reached, the PF will be increased and the counting procedure will be tried another time, until the number of counting responses reaches the threshold or the PF reaches “1”. Then the decision of transmission mode can be acquired. The detailed description of this procedure is shown in FIG. 1.
FIG. 1 is a flow chart showing a conventional counting process between a CRNC 102 and a UE 100 in a wireless communication system. As shown in FIG. 1, in the conventional counting process, in step S101, a CRNC 102 that manages cells sends a signal to provide an initial access probability factor to UE 100 that is located in the cell and starts a counting or recounting. When receiving the initial access probability factor, UE 100 performs the counting response as indicated in step S102. Furthermore, in case UE 100 is in idle mode, UE 100 will establish a Radio Resource Control (RRC) connection. CRNC 102 receives the response from UE 100 and other UEs, and then calculates the total number of the counting responses, as shown in step 103. Then, in step 104, CRNC 102 will compare the counting response number with a predetermined threshold. If the number of the counting responses is greater than the threshold, which means the number of UEs responding to the counting exceeds the threshold, p-t-m mode will be adopted. This is shown in step S107A. If the number of the counting responses is less than the threshold, the CRNC will further check the probability factor to determine whether the probability factor reaches “1”. If the probability factor reaches “1”, the procedure goes to step S107B, in which the counting/recounting procedure finishes and p-t-p mode is applied to establish the connection. This represents the situation that only a few UES request the service and p-t-p mode is capable of meeting the requirement of the connection. Turning back to step S105, if the probability factor does not reach “1”, the CRNC 102 will updates the probability factor and further forward it to the UEs, as shown in step S106. Then steps S102 to S104/s105 will be repeated until an optimum connection mode is determined.
However, there are problems with the above illustrated solutions. To be specific, in case UE 100 is in idle mode, the CRNC and those UEs which respond to the counting will hold the RRC connection therebetween uninterruptedly until the whole counting period finishes. If the decision is adopting p-t-m mode, those RRC connection will be released by CRNC. In this regard, the following problems appear: the radio resource is occupied but not utilized for a long time, which results in the waste of UMTS Terrestrial Radio Access Network (UTRAN) radio resource (such as code resource, transport resource and DL power); since the connection lasts to the end of the counting period, UEs will consume more power, which results in the waste of power; and the RRC connection also causes interferences to other users.
Accordingly, it would be desirable to provide a method and a system for providing an efficient counting in a MEMS environment to overcome the above disadvantages.